Abstract: Tracing hydraulic fractures, stimulations, selective cement jobs, etc. in oil and gas wells includes introducing into a well in a zone of interest a plurality of radio frequency transmitting elements each having an identification, moving in the well a reader tool operative for transmitting radio waves so as to generate and send a radio frequency signal for activating the radio frequency transmitting elements and thereafter to receive a signal returned from the corresponding radio frequency transmitting elements together with the identification of each radio frequency transmitting element, and analyzing data related to the sending of the radio frequency signal from the reader tool to the radio frequency transmitting element and the receiving of the radio frequency signal from the radio frequency transmitting elements with the identification of the radio frequency transmitting elements, so as to trace a corresponding hydraulic fracture, stimulation, selective cement job, etc., in the zone of interest.